**1. Introduction**

History of several bank failures evidences how the excessive risk taking can affect the whole economy as well as the global financial scenario. Since bank deals with different kinds of risks, the regulators strive to minimize this risk exposure through different regulations. The key regulations aiming to minimize the risk and bank failure is the capital adequacy regulation. The principle of the capital adequacy regulation is based on the fact that the minimum capital should be high enough to absorb the potential losses. While capital acts as a buffer for the bank, in the distressed period, the higher the buffer, the lower the risk of default. Therefore, the importance of maintenance of adequate level of capital is never overestimated. This chapter will present a brief history of capital adequacy regulation and the evolution of the regulation over time.
